问题 问答题

在赤道上的地磁场可以看成沿南北走向的匀强磁场,磁感应强度的大小是0.5×10-4T.如果赤道上有一根沿东西方向的直导线,长为20m,载有从东到西的电流30A.地磁场对这根导线的作用力有多大?方向如何?

答案

匀强磁场方向为由南向北,而电流方向为从东向西.则由左手定则可得安培力的方向为竖直向下.

安培力的大小为F=BIL 

解之得 F=3×10-2N    

答:导线受到的安培力大小为3×10-2N;   

方向为竖直向下.

写作题

阅读下面短文,然后按要求写一篇150词左右的英语短文。

The officials in the White House and CIA (中央情报局)are rejecting Edward Snowden's beg for mercy. “Mr. Snowden has been against the U.S. law,” White House adviser Dan Pfeiffer said on Sunday about the former systems analyst who has turned fugitive (逃亡者) in Russia. “He should return to the US and face the justice and judgment, and there is no possibility for mercy and forgiveness.”

However, many people support Snowden and a sociology professor Svallfors in Sweden has recommended Snowden for the Nobel Peace Prize for his “heroic effort at great personal cost” disclosing the spying conducted by the National Security Agency of United States. He wrote, “Because of his bravery, Snowden helped to make the world a little bit better and safer”.

It may be too late for Snowden to receive the award this year, but the nomination should be taken seriously by the Nobel Prize committee for next year’s prize. If Snowden is awarded the prize in 2014, he would be the youngest Nobel Peace Winner in the history of the prize.

【写作内容】

1.以约30词概括上文的主要内容。

2.以约120词发表你对“Information Security”的看法,内容包括:

(1)简述信息安全的重要性;

(2)请举例说明信息安全事故的危害;

(3)谈谈如何维护信息安全。

【写作要求】

1.作文中可以使用亲身经历或虚构的故事,也可以参照阅读材料的内容,但不得直接引用原文中的句子。

2.作文中不能出现真实姓名和学校名称。

【评分标准】

概括准确,语言规范,内容合适,语篇连贯。

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